Field of the Invention
The invention relates to a printing machine cylinder, especially a rubber blanket cylinder, for a web-fed or sheet-fed rotary offset printing machine, having a layer which is protective against corrosion, and to a method for producing such a printing machine cylinder.
Printing machine cylinders installed in modern printing machines, especially rubber blanket cylinders of web-fed or sheet-fed rotary offset printing machines, have been known heretofore to be coated with an anti-corrosion protective layer to prevent corrosion of the cylinder surface. In the case of printing machine cylinders having cylinder bodies which are formed by foliated or globular gray cast iron or steel, for example, anti-corrosion protection is effected after manufacture, by phosphating and oiling the surface of the cylinder jacket. Because the oiling in these cylinders represents the sole protection against corrosion of the cylinder surface, it is often observed that the cylinder surface in the region of damage exhibits marked traces of corrosion, and that the locations where the film of oil was removed, marked corrosion phenomena occur, which no longer permit such a cylinder to be used in a printing machine and persistently impair printing quality, respectively.
It has also become known in the prior art to plate printing machine cylinders with chromium or nickel or to coat them with a sprayed film of fine or high-grade steel.
Besides the comparatively high costs of coating, in these coating methods, as a rule, post-machining of the cylinder-jacket or outer cylindrical surface is necessary, and the aforementioned coatings can, as a rule, be made only whenever the fittings secured to the cylinder bodies, such as bearing rings, flanges, and so forth are removed beforehand.